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Search Results: 1 - 10 of 2380 matches for " Patricio Orio "
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Simple, Fast and Accurate Implementation of the Diffusion Approximation Algorithm for Stochastic Ion Channels with Multiple States
Patricio Orio, Daniel Soudry
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0036670
Abstract: Background The phenomena that emerge from the interaction of the stochastic opening and closing of ion channels (channel noise) with the non-linear neural dynamics are essential to our understanding of the operation of the nervous system. The effects that channel noise can have on neural dynamics are generally studied using numerical simulations of stochastic models. Algorithms based on discrete Markov Chains (MC) seem to be the most reliable and trustworthy, but even optimized algorithms come with a non-negligible computational cost. Diffusion Approximation (DA) methods use Stochastic Differential Equations (SDE) to approximate the behavior of a number of MCs, considerably speeding up simulation times. However, model comparisons have suggested that DA methods did not lead to the same results as in MC modeling in terms of channel noise statistics and effects on excitability. Recently, it was shown that the difference arose because MCs were modeled with coupled gating particles, while the DA was modeled using uncoupled gating particles. Implementations of DA with coupled particles, in the context of a specific kinetic scheme, yielded similar results to MC. However, it remained unclear how to generalize these implementations to different kinetic schemes, or whether they were faster than MC algorithms. Additionally, a steady state approximation was used for the stochastic terms, which, as we show here, can introduce significant inaccuracies. Main Contributions We derived the SDE explicitly for any given ion channel kinetic scheme. The resulting generic equations were surprisingly simple and interpretable – allowing an easy, transparent and efficient DA implementation, avoiding unnecessary approximations. The algorithm was tested in a voltage clamp simulation and in two different current clamp simulations, yielding the same results as MC modeling. Also, the simulation efficiency of this DA method demonstrated considerable superiority over MC methods, except when short time steps or low channel numbers were used.
Quantitative Analysis of Cell Migration Using Optical Flow
Katica Boric, Patricio Orio, Thierry Viéville, Kathleen Whitlock
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0069574
Abstract: Neural crest cells exhibit dramatic migration behaviors as they populate their distant targets. Using a line of zebrafish expressing green fluorescent protein (sox10:EGFP) in neural crest cells we developed an assay to analyze and quantify cell migration as a population, and use it here to characterize in detail the subtle defects in cell migration caused by ethanol exposure during early development. The challenge was to quantify changes in the in vivo migration of all Sox10:EGFP expressing cells in the visual field of time-lapse movies. To perform this analysis we used an Optical Flow algorithm for motion detection and combined the analysis with a fit to an affine transformation. Through this analysis we detected and quantified significant differences in the cell migrations of Sox10:EGFP positive cranial neural crest populations in ethanol treated versus untreated embryos. Specifically, treatment affected migration by increasing the left-right asymmetry of the migrating cells and by altering the direction of cell movements. Thus, by applying this novel computational analysis, we were able to quantify the movements of populations of cells, allowing us to detect subtle changes in cell behaviors. Because cranial neural crest cells contribute to the formation of the frontal mass these subtle differences may underlie commonly observed facial asymmetries in normal human populations.
Corporate and State Social Responsibility: A Long-Term Perspective  [PDF]
Rosetta Lombardo, Giovanni D’Orio
Modern Economy (ME) , 2012, DOI: 10.4236/me.2012.31013
Abstract: Companies have caught the changes in consumer perceptions and have developed corporate social responsibility (CSR) as long run survival strategy. The CSR signals that companies are overcoming the logic of the short term. The question is whether an evolution towards something similar that we call State social responsibility (SSR) is possible. State social responsibility is exerted when the State, in absence (or in case of ineffectiveness) of a formal supranational law, protects the rights of current and future generations of its citizens and citizens of other states and/or raises the current generations’ awareness regarding the opportunities reduction generated in space and time by meta-externalities. States would signal the tendency to overcome their short-sighted logic if the meta-externalities became a crucial question in their agenda.
X-ray observations of classical and recurrent novae in Outburst
M. Orio
Revista mexicana de astronomía y astrofísica , 2004,
Abstract:
Counter-Aging in the Post-industrial Society
Orio Giarini
Cadmus , 2012,
Abstract:
Science and Economics: The Case of Uncertainty & Disequilibrium
Orio Giarini
Cadmus , 2011,
Abstract:
Updating macro-economics
Orio Giarini
Cadmus , 2010,
Abstract:
Observations of Classical and Recurrent Novae with X-ray Gratings
Marina Orio
Physics , 2012,
Abstract: X-ray grating spectra have opened a new window on the nova physics. High signal-to-noise spectra have been obtained for 12 novae after the outburst in the last 13 years with the Chandra and XMM-Newton gratings. They offer the only way to probe the temperature, effective gravity and chemical composition of the hydrogen burning white dwarf before it turns off. These spectra also allow an analysis of the ejecta, which can be photoionized by the hot white dwarf, but more often seem to undergo collisional ionization. The long observations required for the gratings have revealed semi-regular and irregular variability in X-ray flux and spectra. Large short term variability is especially evident in the first weeks after the ejecta have become transparent to the central supersoft X-ray source. Thanks to Chandra and XMM-Newton, we have discovered violent phenomena in the ejecta, discrete shell ejection, and clumpy emission regions. As expected, we have also unveiled the white dwarf characteristics. The peak white dwarf effective temperature in the targets of our samples varies between ~400,000 K and over a million K, with most cases closer to the upper end, although for two novae only upper limits around 200,000 K were obtained. A combination of results from different X-ray satellites and instruments, including Swift and ROSAT, shows that the shorter is the supersoft X-ray phase, the lower is the white dwarf peak effective temperature, consistently with theoretical predictions. The peak temperature is also inversely correlated with t(2) the time for a decay by 2 mag in optical. I strongly advocate the use of white dwarf atmospheric models to obtain a coherent physical picture of the hydrogen burning process and of the surrounding ejecta.
La teoría del caos
Patricio
Política y cultura , 2008,
Abstract:
User Requirements for Effective Access to Digital Archives of Manuscripts
Maristella Agosti,Nicola Orio
Journal of Multimedia , 2012, DOI: 10.4304/jmm.7.2.217-222
Abstract: The availability of digital multimedia resources for cultural heritage poses challenging questions about the kind of interaction that is necessary to foresee to make them available to distinct categories of users. We report on a study on user requirements carried out on two groups of users: domain professional researchers, who need to carry out their research exploiting the functions of digital archives, and non-domain researchers, who need to enhance their experience of digital content and do not have a specific research interest for the digital content. A digital archive of illuminated manuscripts, called IPSA, has been used as a case study for recollecting user requirements. The results highlighted a number of additional requirements by specialized and by non-domain users. The relations between these outcomes provide relevant insights into the role of digital resources for the study and dissemination of cultural heritage.
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